Art of making xanthin.



UNIT D STATES Patented August 9, 1904.

PATENT OFFICE.

MITFORD C. MASSIE, OF WVASHINGTON, DISTRICT OF COLUMBIA, ADMINIS- TRATOROF FRITZ AOH, DECEASED, ASSIGNOR TO C. F. BOEHRINGER & SOEHNE, OFNIANNHEIM-INALDHOF, GERMANY, A FIRM.

ART OF MAKING XANTHIN.

SPECIFICATION forming part of Letters Patent No. 767,353, dated August9, 1904.

Application filed January 6, 1903. Serial No. 138,063. (No specimens.)

To all whom it 7nay concern.-

Be it known that FRITZ AoH, deceased, late a citizen of Germany, and aresident of Mannheim, Germany, did invent new and useful Improvements inthe Preparation of Xanthins; and I, MITEQRD G. MAssIE, a citizen of theUnited States, and a resident of Washington in the District of Columbia,the duly-constituted administrator of the estate of said FRITZ AeH,deceased, do hereby declare the following to be a full, clear, and exactdescription of the said invention of said decedent, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to the art of preparing Xanthin, the object ofthe same being to add new starting materials to those already availablefor this purpose, and in particular such starting materials as will leaddirectly or indirectly to economy in the production of this member ofthe purin series.

The inventor found that thioxanthin may be converted into xanthin properby adopting proper methods of oxidation. By the reactions which hedevised for this purpose the sulfur atom is eliminated either as S02 or1 1280}, according to the selection of the oxidizing agent.

The present invention,therefore, in its broad aspects, consists inreacting on thioxanthin with desulfurizing agents, which agents in thepresent case are oxidizing reagents.

This invention,moreover, consists in such further methods and featuresas will appear from the specification and as will be pointed out in theclaims annexed.

In order to furnish a full and suflicient disclosure of this invention,a number of examples embodying what is considered the preferred mannerof practicing the invention will now be recited.

Erample A 0. 1. ()m'clz'z'lng thioxanthin in acid .\=0lut'l0n.Fiftyparts, by weight, of thioxanthin are suspended in three hundred parts,by volume, of fuming hydrochloric acid, and to this mixture a solutionof sixty parts,

- by weight, of solution of sodiumnitrite weight, of water, is graduallyadded during a period of three hours, the whole being kept at roomtemperature and stirred or agitated during this entire time. After thisthe stirring is continued for further two hours, and the whole is thendiluted with an equal amount, by weight, of water, and then heated onthe water-bath. Any unchanged thioxanthin remaining is left undissolvedin this operation and is removed by filtration. The solution isconcentrated by evaporation in cacao until a strong separation orprecipitation'of xanthinchlorid takes place. The separatedXanthinchlorid is then dissolved in alkali and from this alkalinesolution free xanthin is precipitated by means of acetic acid.

Example 1V0. 2. Oxidation 0 f thioxanthin to want/tin in alkalines0hlt'l0n.Five parts, by weight, of thioxanthin are dissolved in onehundred and seventy parts, by weight, of water and thirty parts, byvolume,of ten times normal carbonate-of-soda solution (Na2CO3) in thewater. The same is then cooled, and this cooled clear solution has thenadded to it ten parts, by volume, of a thirty-per-cent. solution ofhydrogen peroxid, (corresponding to somewhat over one molecule,) thesolution being cooled during the entire time during which the peroxidsolution is added. The whole is then allowed to stand for several hoursand filtered, so as to separate the solution from a small quantity of afinely-granular precipitate, consisting of the sodium salt of theunchanged thioxanthin. The filtrate is then further treated by carefullyadding to it dilute hydrochloric acid until it reacts weakly alkaline,at which stage an amorphous precipitate is thrown down in copiousquantity, sulfurous acid escaping at the same time. If now the whole isboiled down after having added an excess of acetic acid, Xanthin will beseparated in granular form and may then be isolated and further purifiedby known methods.

Ewavnp le 1V0. 3. Oxidation 0 f thiomant/n'n to manta Zn in neutrals0lali0n.Five parts of thioxanthin, together with four hundred parts ofwater and thirteen parts of finely-pulverized peroxid of manganese,(MnO2,) are boiled with the aid of the reflux-cooler. After boiling forabout twelve hours the whole is made slightly alkaline while hot andthen filtered. The filtrate is then acidulated with acetic acid, whichcauses the xanthin, mixed somewhat with thioxanthin, to be thrown down.The precipitate being separated from the mother-liquor, the thioxanthinis removed therefrom by boiling with dilute hydrochloric acid, whichdissolves only the xanthin. From this solution the xanthin is obtainedby the method described under Example N o. 1.

From the above it will be noted that the reagents at starting may beeither in solution or in suspension. This fact is expressed in thegeneric claims by the employment of the term bath, which covers both.

WVhile said FRrrz AoH in illustration of the invention, genericallyconsidered, has described methods of oxidizing thioxanthin in alkalineand neutral baths or solutions, such methods are not herein claimedspecifically, since they are thus covered in divisional applications,Serial Nos. 189,047, (M,) and 189,0et8, (N,) respectively, filed January14, 1903.

lVhat is claimed, and desired to be secured by Letters Patent of theUnited States, is

1. The process of preparing xanthins which consists in causing anoxidizing agent to act on a thioxanthin.

2. The )rocess of )re )arin xanthin which consists in acting upon a bathcontaining thioxanthin with an oxidizing agent.

3. The process which consists in acting upon a solution of thioxanthinwith an oxidizing agent.

4. The process which consists in acting upon an acid-bath of thioxanthinwith sodium nitrite.

5. The process which consists in acting upon an acid-bath of thioxanthinwith an aqueous solution of sodium nitrite.

6. The process which consists in acting upon an acid-bath of thioxanthinwith an aqueous solution of sodium nitrite and then diluting with water,and heating.

7 The process which consists in suspending thioxanthin in fuming HCl inthe proportions substantially as stated and stirring substantially atroom temperature and then, after the lapse of some time, adding asolution of sodium nitrite in Water in the proportion stated, and,finally, adding water in the proportion substantially stated and heatingon the water-bath. I

In testimony whereof I aflix my signature in presence of two witnesses.

MITFORD C. MASSIE, Administrator of the estate of Fmftz Ac/t, da-

ceased.

Witnesses:

L. T. GREIs'r, ALBANUs S. .1. J OIINSON.

